Co-creation and user-generated content-elderly people's user requirements. - Amela Karahasanovic; Petter Bae Brandtzæg; Jan Heim; Marika Lüders; Lotte Vermeir; Jo Pierson; Bram Lievens; Jeroen Vanattenhoven; Greet Jans (Comput. Hum. Behav., 2009)